Molecular interactions and correlation phenomena between pressure shift and solvent shift: a spectral hole-burning study

Pschierer, H.; Friedrich, J.; Falk, Heinz; Schmitzberger, Wolfgang

doi:10.1021/j100128a026

Cited by 30 publications

(28 citation statements)

References 1 publication

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“…It seems that such a behavior is specific for proteins. For instance, when alcohol glass was measured with several quite different dye probes, there was no dye specific difference in the respective slopes (27). The conclusion is that, although proteins have very much in common with glasses, they are different.…”

Section: Discussionmentioning

confidence: 97%

“…p -o 1 would imply that there were no pressure broadening; hence, the obvious conclusion would be that pa-1 is unrealistic. However, from all that we know from numerous experiments on glasses (27)(28)(29)(30), this is not the case. If p = 1 is possible, where does the broadening r come from?…”

mentioning

confidence: 96%

“…Previous studies measured compressibilities by using the hole-burning technique to study MP-HRP at pH 5 (22), protoprophyrin-substituted myoglobin (24), and a series of alcohol glasses doped with several dyes (27,(29)(30)(31). We stress that the results obtained fit well into the scenario known from other experiments, such as sound velocity measurements (32), Brillouin scattering (33), and mechanical experiments (34).…”

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confidence: 99%

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Spectral hole burning and selection of conformational substates in chromoproteins.

Friedrich

Gafert

Zollfrank

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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We investigated spectral holes burnt at 1.5 K into the origins of several tautomeric forms of mesoporphyrin IX-substituted horseradish peroxidase at pH 8 under pressures up to 2 MPa. From the pressure-induced lineshift the compressibility of the apoprotein could be determined. We found that the compressibility changed significantly when measured at different tautomer origins. It was concluded that there must be a correlation between the tautomer configurations of the chromophore and the actual structures of the apoprotein. As a consequence, specific conformational substates of the protein can be selected by optical selection of the associated tautomers.The solid-state physics of proteins is an intriguing field. Unlike crystals, proteins are finite systems, yet they have a smooth density of vibrational states which is Debye-like at sufficiently small energies (1). Like crystals, proteins are highly ordered (2). Yet disorder plays a very important role, too (3, 4). Disorder manifests itself in inhomogeneously broadened spectral lines, in nonexponential kinetics, in nonArrhenius-type activated processes, in a glass-like specific heat, in dielectric damping, etc. (5-8). Even from x-ray scattering experiments, it became obvious that, at a sufficiently high level of resolution, the structure of a protein is not so well defined (2, 3). There seems to be agreement that a certain extent of structural disorder is a prerequisite for the proper functioning of a protein.A possible model for describing the relation between order and disorder in proteins is based on the concept of conformational substates (4,7,9,10): The basic idea of this model is that a protein can exist in a huge set of substates. Most of these substates are assumed to be in fast equilibrium because their separating barriers are sufficiently small compared with kT. Some ofthem, however, are nonequilibrium states. These special substates may be functionally important. It is structural disorder which gives enough freedom to the protein to reorganize its structure for specific requirements.Here we address the problem of how this reorganization takes place and how this is related to the prosthetic group. Can a slight structural change of the prosthetic group, as induced by a weak chemical interaction, be a signal for the protein structure to be rearranged, for example, to help the binding of special molecules? That is, we address the problem of correlation between the configurations of the prosthetic group and the conformational substates of the protein.The experimental technique we employ is persistent spectral hole burning (11)(12)(13)(14)(15). Hole burning is a special type of saturation spectroscopy. Its specific feature, as compared with similar techniques in NMR and ESR spectroscopy, is the persistence of the hole. This persistence is the reason why the technique can be used to study the ground state by optical means. At liquid-helium temperatures, the width of a spectral hole is close to the natural width of the optical transition involved. For m...

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Section: Discussionmentioning

confidence: 97%

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confidence: 96%

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confidence: 99%

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Spectral hole burning and selection of conformational substates in chromoproteins.

Friedrich

Gafert

Zollfrank

et al. 1994

Proc. Natl. Acad. Sci. U.S.A.

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“…25 Hypericin is also an efficient hole-burning dye. 26 Recently, it has been shown to be present in solutions and complexed to HSA as the dissociated species, the hypericinate ion. 27 The respective photoreaction of the hole-burning process is supposed to be a proton transfer (tautomerization) in the bay region ( Figure 1), which differs from that suggested for quinizarin.…”

Section: Introductionmentioning

confidence: 99%

Hole-Burning Spectroscopy of Proteins in External Fields: Human Serum Albumin Complexed with the Hypericinate Ion

Köhler¹,

Gafert²,

Friedrich³

et al. 1996

J. Phys. Chem.

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We investigated human serum albumin complexed with the hypericinate ion by using optical hole-burning techniques. The response of the burned-in holes to external pressure variations and electric fields was measured as a function of burn frequency within the inhomogeneous band. The results for the protein-dye complex were compared with the respective behavior of the dye in a host glass. In addition, the spectral properties of the serum albumin hypericinate complex in an electric field were compared with the respective properties of protoporphyrin substituted myoglobin. On the basis of our results we concluded that there must be two stereoisomers with a relative weight of about 50%. Further, the binding site in human serum albumin seems to be quite shallow. The dye is not shielded from the host glass, contrary to the respective behavior of protoporphyrin-substituted myoglobin.

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“…Also the shift of spectral holes under pressure ͑up to 2.50 MPa͒ may be accounted for by solvent shift theory. 21,22 The linear shift of a J-band under pressure may be explained simplistically by dye-to-dye distance changes in the aggregate and, hence, changes of dipole-dipole coupling of the London force type. Enhancement of dipolar interaction under pressure is a most plausible scenario which leads to a linear dependence of redshift with P. Indeed, at the end of this section, we will use this idea in an attempt to extract J from our data.…”

Section: Discussionmentioning

confidence: 99%

High pressure investigation of absorption spectra of J-aggregates

Lindrum

Chan

1996

The Journal of Chemical Physics

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The spectral shift of J-bands under high pressure up to 60 kbar has been investigated for J-aggregates of different cyanine dyes. Under conditions where no J-band can be observed at normal pressure, J-aggregates are formed at higher pressure. A red shift of absorption upon increasing pressure was found with a linear dependence of line position on pressure. The results can be explained by a change of dipolar coupling of monomer molecules in the aggregate due to decreasing center-to-center distances. The different pressure slopes of various aggregates are interpreted from their different aggregate structures. The monomer absorption is also red-shifted under pressure, but the pressure dependence is quite different and can be described by a solvent shift. From the linear dependence, the dipole-dipole coupling energy J can be determined with a simple theory. The general applicability and limitations of this method are discussed.

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Molecular interactions and correlation phenomena between pressure shift and solvent shift: a spectral hole-burning study

Cited by 30 publications

References 1 publication

Spectral hole burning and selection of conformational substates in chromoproteins.

Spectral hole burning and selection of conformational substates in chromoproteins.

Hole-Burning Spectroscopy of Proteins in External Fields: Human Serum Albumin Complexed with the Hypericinate Ion

High pressure investigation of absorption spectra of J-aggregates

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